To know when your particular page has been updated, do the following:
Go to the wiki page
Click on manage wiki
Click on notifications
Type in the page name of whatever page you are wanting to monitor
Make sure page edits and discussions both have checkmarks in them
Click on update

To know when the wiki in general has been updated, do the following:
Go to the wiki page
Click on manage wiki
Click on notifications
Leave the page name section blank
Make sure page edits and discussions both have checkmarks in them
Click on update